数据库连接池Demo

c3p0连接池Demo

		/**
		 * c3p0连接池demo
		 * 依赖包:
		 * 		c3p0-0.9.5.2.jar
		 * 		mcchange-commons-java.jar
		 */
		// 创建连接池
		ComboPooledDataSource combo = new ComboPooledDataSource();
		// 从连接池获取连接对象
		Connection conn = combo.getConnection();
		PreparedStatement stmt = conn.prepareStatement("select * from emp");

druid连接池Demo

/**
		 * 依赖包:druid.jar
		 */
		// 类加载器获取配置文件输入流对象
		InputStream is= DruidTest.class.getClassLoader().getResourceAsStream("druid.properties");		
		Properties ps = new Properties();
		ps.load(is);
		// 创建连接池对象
		DataSource ds = DruidDataSourceFactory.createDataSource(ps);
		// 从连接池获取连接对象
		Connection conn = ds.getConnection();
		
		PreparedStatement stmt = conn.prepareStatement("select * from emp");

c3p0加dbUtils

// 依赖包:commons.dbutils.jar
public class DbUtils {
	static ComboPooledDataSource pool = new ComboPooledDataSource();
	static QueryRunner qr = new QueryRunner(pool);
	
	@Test
	public void add() throws SQLException {
		String sql = "insert into `job` values (null,'清洁工','扫地')";
		qr.update(sql);
	}
	
	@Test
	public void delete() throws SQLException {
		String sql = "delete from job where `jname`=?";
		qr.update(sql,"清洁工");
	}
	
	// 得到查询结果的首个对象的数组形式
	@Test 
	public void query1() throws SQLException {
		String sql = "select * from job";
		Object[] obj = qr.query(sql, new ArrayHandler());
		System.out.println(Arrays.toString(obj)); // [1, 董事长, 管理整个公司，接单]
	}
	
	// 得到查询结果的所有对象的数组形式
	@Test 
	public void query2() throws SQLException {
		String sql = "select * from job";
		List<Object[]> obj = qr.query(sql, new ArrayListHandler());
		for (Object[] objects : obj) {
			System.out.println(Arrays.toString(objects));
		}
		/*
		 * [1, 董事长, 管理整个公司，接单] 
		 * [2, 经理, 管理部门员工] 
		 * [3, 销售员, 向客人推销产品] 
		 * [4, 文员, 使用办公软件] 
		 * [5,总经理, 打扫卫生]
		 */
	}
	
	// 得到查询的首个对象的Job对象形式
	@Test
	public void query3() throws SQLException {
		String sql = "select * from job";
		Job j = qr.query(sql, new BeanHandler<>(Job.class));
		System.out.println(j);
	}
	

	// 得到查询结果集的所有对象的Job对象形式
	@Test
	public void query4() throws SQLException {
		String sql = "select * from job";
		List<Job> j = qr.query(sql, new BeanListHandler<>(Job.class));
		System.out.println(j);
	}
	
	// 得到单个查询结果
	@Test
	public void query5() throws SQLException {
		String sql = "select `jname` from job where `id`=1";
		Object obj = qr.query(sql, new ScalarHandler());
		System.out.println(obj);
	}


}